ML20056G200

Safety Evaluation Denying 930419 Request for Relief from Requirements for Hydrostatic Testing of ASME Class 3 Pressure Retaining Components

ML20056G200
Person / Time
Site:	River Bend
Issue date:	08/19/1993
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20056G197	List: ML20056G196 ML20056G200
References
NUDOCS 9309020235
Download: ML20056G200 (3)

Text

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, pmc u jgMM' i E UNITED STATES NUCLEAR REGULATORY COMMISSION g u ,/ WASHINGTON, D.C. 205540001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE INSPECTION PROGRAMS FOR GULF STATES UTILITIES COMPANY RIVER BEND STATION. UNIT 1 DOCKET NO. 50-458

1.0 INTRODUCTION

The technical specification for the River Bend Station (RBS) states that inservice inspection and testing of American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (Code) and applicable Addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).

Paragraph 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (1) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.

In a letter dated April 19, 1993, Gulf States Utilities, (GSU, the licensee),

submitted Relief Request RR0017 proposing an alternative to the hydrostatic test of ASME Class 3 pressure retaining components. The licensee proposed to perform a system pressure test at normal operating pressures and an accompanying VT-2 visual examination. The staff has evaluated the licensee's request and determined that the proposed alternative is not acceptable.

2.0 DISCUSSION Identification of Components Subject to Relief ASME Code Class 3 pressure retaining components, Code categories D-A, D-8, and D-C.

Code Requirements From Which Relief is Requested ASME Section XI, IWD-2500-1, Examination Categories D-A, D-B, and 0-C, Items DI.10, D2.10, and D3.10, require that Class 3 pressure retaining components receive a hydrostatic or pneumatic test and a concurrent VT-2 visual examination once each inspection interval. The purpose of the hydrostatic or pneumatic test is to determine the structural integrity of the pressure retaining components.

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Licensee's Relief Request GSU requested relief from performing the hydrostatic or pneumatic testing requirement of IWD-2500-1.

Basis for Relief In most cases hydrostatic and pneumatic tests performed on ASME Class 3 systems at RBS do not provide meaningful information. This is due to the fact that most ASME Class 3 systems at RBS are water or air systems that have a low design pressure and temperature. There are 12 systems containing 561 ASME class 3 lines. Of those lines, apnroximately 88 percent have a design pressure of 150 psig or less and have a design temperature of less than 200 degrees Fahrenheit. Therefore, in many cases the test pressure is less than 25 psig above actual operating pressure.

ASME Code Case N-498 provides alternative rules for 10-year hydrostatic pressure testing for ASME Class 1 and 2 systems. An alternate should be considered for ASME Class 3 pressure retaining components.

GSU requests relief from hydrostatic and pneumatic testing for ASME Class 3 pressure retaining components. Instead of the current hydrostatic and pneumatic testing, the following alternative testing will be performed:

1. One hundred percent of the required lines will receive a functional or inservice test with a VT-2 visual examination each inspection period in accordance with ASME Code, Section.XI, Class 3 requirements.

2. The boundary subject to test pressurization shall extend to all Class 3 components included in those portions of systems required to operate or support the safety system function up to and including the first normally closed valve (including a safety relief valve) or valve capable of automatic closure when the safety function is required.

3. Prior to performing YT-2 visual examination, the system shall be pressurized to nominal operating pressure for a minimum of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated rystems and 10 minutes for systems which are not insulated. The system shall be maintained at nominal operating pressure during the performance of the VT-2 visual examination.

NOTE - The VT-2 visual examination shall include all components within the boundary identified above.

This alternative to hydrostatic and pneumatic testing provides a number of benefits to GSU. Following are some examples:

1. Decreased radiological waste since filling the system for testing and draining the system after test completion is not required.

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2. Decreased exposure since activities that require additional personnel to be in the test area (e.g., instrumentation isolation, venting, valve realignment, valve tagging, manning test equipment, making test connections, etc...) are limited.

3. Tl.e possibility of overpressurizing interconnecting systems due to unsuspecting valve seat leakage no longer exists.

3.0 EVALUATION The staff evaluated the licensee's submittal as an alternative to ASME Section XI requirements pursuant to 10 CFR 50.55a(a)(3), rather than as a relief request, pursuant to 10 CFR 50.55a(g). The concept of " relief requests" involves the impracticality of ASME Code requirements. In this case, the requirements of IWD-2500-1 can be performed at River Bend without an undue burden and, therefore, the Code requirements are practical. The licensee's submittal describes in very general terms the differences between the required hydrostatic or pneumatic testing and the proposed system pressure tests. The licensee states that in many cases the difference in test pressure between the hydrostatic or pneumatic test and the system pressure test is less than 25 psig. However, the licensee does not present any information that testing at the lower pressure will provide an acceptable level of quality and safety.

The licensee also described some unquantified benefits that would result from approval of the alternate testing. However, the information presented does not support a conclusion that the requirements result in a hardship or unusual difficulties.

Based on the licensee's submittal, the 2,taff could not conclude that the alternative testing would provide an acceptable level of quality and safety.

In addition, the submittal did not support a determination that compliance with the hydrostatic er pneumatic testing requirements would result in hardship or unusual difficulties without a compensatory increase in the level of quality and safety. Based on the those conclusions, the NRC staff finds the relief request unacceptable.

Principal Contributor: D. G. Naujock Date: August 19, 1993